The present invention relates to a data transfer control device, an electronic instrument, and a data transfer control method.
The Universal Serial Bus (USB) 2.0 standard has been developed and has attracted attention as a standard which can implement a data transfer rate of 480 Mbps (HS mode), which is remarkably higher than the data transfer rate in the USB 1.1 standard, while maintaining compatibility with the USB 1.1 standard. Japanese Patent application Laid-open No. 2002-135132 discloses a conventional example of a USB data transfer control device, for example.
The market for the USB 2.0 standard which supports the high speed (HS) mode has grown steadily. The USB On-The-Go (OTG) standard has been developed by the USB Implementers Forum (USB-IF) as a standard which implements a USB simple host. The OTG standard (OTG 1.0) developed as an extension of the USB 2.0 standard has the potential for creating a new added value for the USB interface, and development of applications making use of its characteristics has been anticipated.
A peripheral (peripheral device) which has been connected with a host (personal computer or the like) through the USB can be provided with a host function by utilizing a simple host implemented by the OTG standard or the like. This enables data to be transferred between peripherals by connecting the peripherals through the USB. For example, an image from a digital camera can be printed by directly connecting the digital camera with a printer, or data can be saved by connecting a digital camera or a digital video camera with a storage device.
However, a low performance CPU (processing section in a broad sense) is generally provided in a peripheral provided with the host function by utilizing the OTG simple host or the like. Therefore, if the processing load of the CPU (firmware) included in the peripheral is increased or the processing becomes complicated by the addition of the host function, other processing is hindered or the design period of the instrument is increased.